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The original titles only had the module name, which is not very useful when scanning the list. By adding a very brief description to each title, the table of contents becomes friendlier. Also amend the introduction in the "additional modules" appendix, using the word "Extension" more extensively. Nowadays, almost all contrib modules are extensions, so this is also helpful. Author: Karl O. Pinc <kop@karlpinc.com> Reviewed-by: Brar Piening <brar@gmx.de> Discussion: https://postgr.es/m/20230102180015.372995a9@slate.karlpinc.com
102 lines
3.1 KiB
Plaintext
102 lines
3.1 KiB
Plaintext
<!-- doc/src/sgml/dict-int.sgml -->
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<sect1 id="dict-int" xreflabel="dict_int">
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<title>dict_int —
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example full-text search dictionary for integers</title>
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<indexterm zone="dict-int">
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<primary>dict_int</primary>
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</indexterm>
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<para>
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<filename>dict_int</filename> is an example of an add-on dictionary template
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for full-text search. The motivation for this example dictionary is to
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control the indexing of integers (signed and unsigned), allowing such
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numbers to be indexed while preventing excessive growth in the number of
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unique words, which greatly affects the performance of searching.
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</para>
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<para>
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This module is considered <quote>trusted</quote>, that is, it can be
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installed by non-superusers who have <literal>CREATE</literal> privilege
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on the current database.
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</para>
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<sect2 id="dict-int-config">
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<title>Configuration</title>
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<para>
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The dictionary accepts three options:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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The <literal>maxlen</literal> parameter specifies the maximum number of
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digits allowed in an integer word. The default value is 6.
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</para>
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</listitem>
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<listitem>
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<para>
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The <literal>rejectlong</literal> parameter specifies whether an overlength
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integer should be truncated or ignored. If <literal>rejectlong</literal> is
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<literal>false</literal> (the default), the dictionary returns the first
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<literal>maxlen</literal> digits of the integer. If <literal>rejectlong</literal> is
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<literal>true</literal>, the dictionary treats an overlength integer as a stop
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word, so that it will not be indexed. Note that this also means that
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such an integer cannot be searched for.
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</para>
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</listitem>
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<listitem>
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<para>
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The <literal>absval</literal> parameter specifies whether leading
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<quote><literal>+</literal></quote> or <quote><literal>-</literal></quote>
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signs should be removed from integer words. The default
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is <literal>false</literal>. When <literal>true</literal>, the sign is
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removed before <literal>maxlen</literal> is applied.
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</para>
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</listitem>
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</itemizedlist>
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</sect2>
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<sect2 id="dict-int-usage">
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<title>Usage</title>
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<para>
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Installing the <literal>dict_int</literal> extension creates a text search
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template <literal>intdict_template</literal> and a dictionary <literal>intdict</literal>
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based on it, with the default parameters. You can alter the
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parameters, for example
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<programlisting>
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mydb# ALTER TEXT SEARCH DICTIONARY intdict (MAXLEN = 4, REJECTLONG = true);
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ALTER TEXT SEARCH DICTIONARY
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</programlisting>
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or create new dictionaries based on the template.
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</para>
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<para>
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To test the dictionary, you can try
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<programlisting>
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mydb# select ts_lexize('intdict', '12345678');
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ts_lexize
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-----------
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{123456}
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</programlisting>
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but real-world usage will involve including it in a text search
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configuration as described in <xref linkend="textsearch"/>.
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That might look like this:
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<programlisting>
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ALTER TEXT SEARCH CONFIGURATION english
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ALTER MAPPING FOR int, uint WITH intdict;
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</programlisting>
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</para>
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</sect2>
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</sect1>
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